In its statement, the credit rating agency said that the rating reflected “Moody’s assessment of AIIB’s current and future creditworthiness, as it ramps up its operations over the next 5-10 years”.

Moody’s became the first international credit rating agency to assign rating to the AIIB, which was established in 2015 with 57 member countries and US$100 billion in committed capital for funding infrastructure projects across Asia.

The bank has since stepped up its membership to 80 and approved loans worth US$2.5 billion to 16 projects in countries including Bangladesh, India and Pakistan.

China is the AIIB’s biggest shareholder, followed by India, Russia, Germany and South Korea.

The United States and Japan have not joined the bank due to initial concerns about the bank’s standards and possible rivalry with the World Bank and the Asian Development Bank.

Moody’s said it expects the AIIB's liquidity position to be as strong as that of other highly rated multilateral development banks, noting the bank’s paid-in and callable capital was already larger than at more established multilateral lenders.

It said the bank’s credit profile is further enhanced by its broad membership and the likelihood that further support would be made available by “shareholders with a strategic interest in sustaining the bank's operations – including but not limited to China”.

But Moody’s said the rating rested on the assumption that the AIIB will retain full operational autonomy from its largest shareholders including China, and that its development strategy will remain broadly focused on infrastructure development in emerging markets.